1. Field of the Invention
The present invention relates to a method of preventing polymer scale deposition on the inner wall surface and so forth of a polymerization vessel during polymerization of a monomer having an ethylenically double bond.
2. Description of the Prior Art
In processes of preparing polymers by polymerizing a monomer in a polymerization vessel, the problem that polymer deposits on the inner wall surface and so forth in the form of scale, is known.
The deposition of the polymer scale on the inner wall results in disadvantages that the yield of the polymer and the cooling capacity of the polymerization vessel are lowered; that the polymer scale may peel and mix into manufactured polymer, thereby impairing the quality of the manufactured polymer; and that removal of such polymer scale is laborious and hence time-consuming. Further, since the polymer scale contains unreacted monomer and operators may be exposed thereto, which may cause physical disorders in the operators.
Heretofore, as methods for preventing polymer scale deposition on the inner wall surface and so forth of a polymerization vessel, methods in which a suitable substance is coated on the inner wall surface, etc. as a scale preventive agent.
As the suitable substance acting as a scale preventive agent, there has been disclosed, for example, a dye or pigment (Japanese Patent Publication (KOKOKU) Nos. 0835/1975, and 24953/1977), reaction products of a phenolic compound and an aromatic aldehyde (Japanese Pre-examination Patent Publication No. 54317/1980), etc.
However, the prior art polymer scale preventive agents composed of the substances described above include a great number of colored substances as exemplified typically by the dyes and pigments described in Japanese Patent Publication (KOKOKU) No. 30835/1970 or 24953/1977, the aromatic amine compounds described in Japanese Pre-examination Patent Publication (KOKAI) No. 50887/1976, the reaction products of a phenolic compound and an aromatic aldehyde described in Japanese Pre-examination Patent Publication (KOKAI) No. 54317/1980, etc. Where the coating composed of such polymer scale preventive agent is dissolved or peels and then is incorporated into the polymerization system, manufactured polymer may be colored, thereby its quality being lowered.